Stabilized azine photographic developers containing sodium metaborate as the sole alkali



D (By Ansco-Sweet Black G'White Densitometer) R. c. GUNTHER 2,656,272 STABILIZED AZINE PHOTOGRAPHIC DEVELOPERS CONTAINING SODIUM METABORATE AS THE SOLE ALKALI Filed Nov. 50, 1950 Effect of Developer Storage on Maximum Dye Density Storage Time (Days) Robert C. Gunther INVENTOR.

A TTORNE Y5 a Patented Oct. 20, 1953 STABILIZED AZINE PHOTOGRAPHIC' DE VELOPERS CONTAINING SODIUM META- BORA'IE AS THE SOLE ALKALI Robert C. Gunther, Galesburg, Ill., assignor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware Application November 30, 1950, Serial No. 198,396 7 Claims. (Cl. 95-88) The present invention relates to stabilizedazine photographic developers, and particularly such developers in which stabilization has been effected by replacing the sodium carbonate generally employed as the alkali by sodium metaborate.

United States Letters Patent.2,486,440 granted November 1, 1949, to Schmidt and Tulagin, and my United States Letters Patent 2,570,116, issued Ofctober"2,' 195 describe azine color developers in whichthe essential components are a 2,4-diamino aniline and an alkali, specifically sodium carbonate.

In order to be commercially feasible, a developer for the production of azine dye images in photographic elements shouldpossess the, following general characteristics:

(a)v Good storage stability; I

- (b). The ability-to produce maximum. dye-densityin minimum time;

(c) The ability to produce a minimum of proximity development; and

(d) Satisfactory development characteristics. suchaas rate of development, slow rate of exhaustion, and the like.

The effective developing agent-in the azine developers described-in the foregoing patent and application, being a diamino aniline derivativais very susceptible to. aerial oxidation, and this-factor has. long presented a, seriousv stabilityproblem in the-preparationand use of azine color developer solutions.

Although the storage. stability requirements for an azineecolori developer cannotbetoo well defined, nevertheless it is felt that-such a developer should-be stable, with moderate .useforyat least a week to ten days-withoutchange in its color development properties.

Efforts have been made. to. improve-the storage stability of the. azineedevelopers bydncludr ingcomponents-specifically designedtto preserve the.v developers. To; this endtherehave, beenused dextrose, hydroxylamine, p-hydroxyphenyl-. glycine and Rongalite,- among others. While. certain of thesescompounds, specifically, hydroxylamine, have a definitev stabilizing action, each of thexcompounds tested had adeleterious effect on thetdevelopment-properties of the color developers. Thus,-. dextrose, p-hydroxyphenylglycine and Rongalite decrease the, development potential- On the other; hand, the hydroxylamine causes a seriousloss in color rendition by increasinggproximity development.

Iniyiew of the-results involving ;-the employment of additives,=, to: improvea azine developer. Sta-,- bility, it was realized that some other means would haves to: be foundi, if developers of satisfactory storage stability were to be. produced. As azresult of thisconclusion, Idiscovered, rather surprisingly, that developers of satisfactory stability could be obtained by replacingjthe sodium carbonate used to supply alkalinity to the known azine developers by sodium metaborate. By this substitution ofthe sodium metaboratefor sodium carbonate, it Was found that the developers with the sodium metaborate. were many times: more stable than the developers containing sodium carbonate.

Color developers of the, 2,4-diaminoaniline class, containing sodium metaborate, as the alkali and as a stabilizer for the developer, constitute the purposes and objects of the present invention;

The quantity of the sodium metaborate which I found to be eifective ranges from about 30 to 50 parts per liter of developer. With this amount of sodium metaborate, the stability of the developer composition is two to threetimes as great as the stability of a corresponding developer containing sodium carbonate as the alkali. Such improved stability manifests itself not only by a slower darkening rate of the solution itself, but

also by an improved color brilliance and maximum dye. density.

It is evidentfrom what has been said, thatthe essential, components. of my developer are a I 2 ,4-diaminoaniline as the effective reducing agent and sodiumrmetaborate as the alkali. As the 2,4-diaminoaniline. I, may usexany one of those which are described. in the aforesaid United States Letters Patent 2,486,440,- or in my afore said U. S. Patent 2,570,116.

Examples of such 2,.4-diaminoanilinesare: 4- (s-hydroxyethylamino) -6 phenylaminometanilic acid; 4,6-di (B-hydroxyethylamino) -metani1ic acid; 4-(5 hydroxyethylamino) -6-(4-carboxymethoxyphenylamino) -metalinic acid; 4-(0- methoxyphenylamino) 6-- (p methoxyphenylsuggests the utilization of amino. pyridines forv It is, therefore.,-,advisable to the same purpose.

include either a phenol or an amino pyridine in the developer, to reduce proximity development. Sodium sulfate, which is also found to have a similar effect, may also be employed.

In my U. S. Patent 2,623,823 I discuss energizers for ZA-diaminoaniline developers, which are the reaction product of such a developer, with an aldehyde or pyruvic acid, or a derivative thereof. Such compounds also aid in giving a developer of optimum characteristics.

The proportions of the various components in the developer may vary, but I have found that the developers constituted as noted below are very effective:

Parts A ZA-diaminoaniline 4 to 8 Sodium metaborate anhydrous 20 to 60 An alkali metal sulfite 20 to 60 An alkali metal bromide 1 to 5 An amino pyridine 1 to 20 The reaction product of a ZA-diamino aniline with an aldehyde or with pyruvic acid or a derivative thereof 2 to 4 A phenol to 10 Sodium sulfate 50 to 150 Ascorbic acid 0 to 3 Water to make 1000 It is evident that the ascorbic acid is not necessarily present in the developer. It has been found, however, that while ascorbic acid in a developer containing sodium carbonate as the alkali is not a satisfactory stabilizer, nevertheless when used in a developer containing sodium metaborate as the alkali, it increases the stability beyond that afforded by the sodium metaborate alone. Consequently, for best results it is preferred to include ascorbic acid in the composition.

The following examples will serve to illustrate developer compositions for the azine synthesis, which I have found to have a storage stability much greater than that possessed by known developers containing sodium carbonate as the alkali.

EXAMPLE 1 Grams e-(fi-hydroxyethylamino) 6 phenylamino metanilic acid 5 Sodium metaborate (86%) 30 Sodium sulfite 60 Potassium bromide 1 2-amino pyridine 15 The reaction product of pyruvic acid with 4- (c hydroxyethylamino) -6-phenylamino metanilic acid 3 Sodium sulfate 100 Water to make 1000 cc.

(Hereinafter referred to as the Energizer) EXAMPLE 2 The composition is the same as Example 1, excepting that it includes 1 gram of ascorbic acid.

Water to make 1000 cc.

4 EXAMPLE4 The composition is the same as that of Example 3, excepting that it includes 1 gram of ascorbic acid.

In order to establish the improvement wrought by the utilization of sodium metaborate, in lieu of sodium carbonate, in azine developers, I compounded the following developers for comparison with those of the examples.

Grams l-(fi-hydroxyethylamino) 6 phenylamino metanilic acid 5 sodium carbonate monohydrate 40 Sodium sulfite 50 Potassium bromide 5 Pyridine 16 Benzylamine 1 Phenol (in cc. of 10% trisodium phosphate) 10 Energizer 2.5 Water to make 1000 cc.

Grams 4-(p-hydroxyethylamino) 6 phenylamino metanilic acid 5 Sodium carbonate monohydrate 40 Sodium sulfite 60 Potassium bromide 5 2-amino pyridine 16 Phenol (in 100 cc. of 10% trisodium phosphate) 10 Energizer 2.5 Water to make 1000 cc.

Reference is here made to the fact that the proportioning of the ingredients in these two developers is designed to give optimum results with the components employed.

There are three methods known for comparing the stability of the developers containing sodium carbonate on the one hand, and those containing metaborate on the other hand, and these are as follows:

(1) Comparison of color of the stored developer compositions;

(2) Comparison of maximum density on development of the same sensitometric, photographic strips at various periods of developer storage time; and

(3) Comparison of relative color brilliance of the spectrograms photographically developed in the aged developer solutions.

The first comparison is a visual one, and hence requires no detailed discussion.

In making the other two comparisons, I utilized as the sensitometric strips, azine multilayer film prepared as follows:

On a film base was cast a red sensitive silver halide emulsion layer containing as a. cyan color former. one of the fast to diffusion aryl J acids described in U. S. Patent 2,591,642. On the red sensitive layer was cast a green sensitive silver halide emulsion layer containing as the magenta color former, one of the fast to diffusion 8-hydroxy quinolines disclosed in United States Letters Patent 2,524,725 granted on October 3, 1950, to Robert F. Coles. Over the green sensitive layer was cast a blue sensitive silver halide emulsion layer containing as the yellow color former, one of the benzimidazole derivatives, fast to diffusion, described in United States Letters Patent 2,500,- 487 granted on March 14, 1950 to Winfred C. Craig.

Each film prepared as above was utilized by exposing it to a spectrum,- developing '"it' in black and white; 're-' exposing and developing it irrtl ie test solution; 1. e: the'solutions containing-"sodium:carbonatejchararcterized aswAwandaB abova and the solutions-oft the? examples.:.

The'specifie procedureffollowed in utilizing such color developers involves the following steps:

('13) Spectrogramsi were madei usingrfreshr developer solutiom; v

(2) The developers were stored twelve days withperiodic use, 400 square'inches of azine color mm being developed per'liter of" solution; 1

(3) Spectrogramsweremade'using theoldidevelopers: ii e; after'twelve' dayststorager My,

. (4-) Colondensitymeasurements weremade'on the spectrograins' from the'freslr'developer' solutions (before), and from the old developer solutions (after).

The results of these tests are indicated in the table below, it being pointed out that developer 1 in said table is solution A above, containing sodium carbonate, 2 is solution B above containing sodium carbonate, and 3 to 6 inclusive corresponding to Examples 1 to 4, respectively.

whatsoever.

Heferenc'e has-previously beenlmade tothetf-act that ascorbic acid, when present in a: small amount in a developer containing metaborate, further promotes the stability: of the developer. This fact-is emphasized bythis" additional test: Developers lto-5 ofthe table were allowed to stand in capped-amberbottles for-two months after the tests described in the table were com pleted. Attheend of this time,-all of the develop ers, except 4, were. a-very-dark red .color. Developen 4, the only. one containingascorbicacid, was still a light orange-yellow color. Upondevelopment of step wedges and spectrograms with the 5 solutions, No. .4 produced images of excellent .bril-e liance and 1 very clearwhites, whereas none: of the: other. developersv produced any: dye image It will thus be seen that asmall amount of ascorbic acid operates to greatly promote the stabilizing effect of the sodium metaborate.

It has been proposed in the past to utilize sodium meta'borate in fine grain black and white developers, and, in fact, this product is commercially offered for use in this relationship. There is no suggestion, however, in any prior art which TABLE Relative Color Relative Developer Brilliance Stability D max. dr 6401.4 D Developer D max. (a) Color of Solution Number dr 640p. 640 (a) After Storage m X Before After Before After Before After dr 64014 (b) 2.35 1. 77 0. 29 0.55 8.1 3. 2 39. 5 Deep red. 2.02 1. 70 0.25 0.50 8.1 3. 4 42. 0 D0. 2. 26 2. 08 0. 19 0. 33 ll. 9 6. 3 52. 9 Orange-yellow. 2.10 1. 93 0.18 0.21 11. 7 9. 2 78. 6 Yellow. 2. 38 2. 29 0. 19 0.29 12. 5 7. 9 63. 2 Orange-yellow. 2. 3O 2. 16 0. 18 0. 21 12. 8 10. 3 80. 5 Yellow.

Norris:

(2) (it in the table refers to the cyan density through the red filter at (3) The color brilliance of any one spectrum was cyan density through a red filter at 640 taken as the ratio of the maximum neutral density to the (4) The maximum density was determined by use of the commercial Ansco-Sweet black and white densitometer.

It will be observed that this table gives not only the color change of the solutions on storage, but also gives the maximum densities and relative color brilliance of the fresh solutions and of the solutions upon aging. It will also be observed that the developers containing sodium metaborate are far and away more stable than those containing sodium carbonate.

Attention is also directed to the attached drawing which shows graphically the effect of development storage on maximum dye densities of the six solutions of the table.

It will be appreciated that solution 2 is very similar to solution 5, excepting that a small amount of phenol is present in solution 2. By comparing curves '2 and 5 of the drawing, after twelve days storage, it will be found that the metaborate containing developer showed a loss of Dmax of .1 of a unit, whereas the carbonate containing developer over the same storage time showed a loss in Dmax of .3 of a unit.

Curve 3 indicates that by storage of the developer thereof for twelve days, the loss in Dmax is only .15 of a unit. If an attempt be made to alter the formula of developer composition of curve 5 by substituting half of the sodium meta borate by sodium carbonate, a developer composition results which possesses storage properties much inferior to those of the developer of curve 5.

would lead one to believe that sodium meta'borate has a very marked stabilizing effect on azine developers when used as the alkali thereof.

Various modifications of the invention will be apparent to persons skilled in the art, and I, therefore, do not intend to be limited in the patent granted except as required by the appended claims.

I claim:

1. A storage stable developer solution for the production of azine dyestuff images containing a 2,4-diaminoaniline and sodium metaborate as the only alkali for the developer.

2. The composition as defined in claim 1, wherein the 2,4-diaminoaniline is 4-( s-hydroxyethylamino)-6-phenylamino metanilic acid.

3. The composition as defined in claim 1, containing in addition, sodium sulfite and potassium bromide.

4:. The composition as defined in claim 1, wherein the sodium metaborate is present in a concentration of from to grams per liter of developer solution.

5. A storage stable developer solution for the preparation of azine dye images containing 4- (fl-hydroxyethylamino) -6-phenylamino metanilic acid, sodium metaborate as the only alkali for the developer and a small amount of ascorbic acid.

6. A storage stable developer solution for the preparation of azine dye images of the iollowin composition:

Parts A 2,4-diaminoaniline 4 to 8 Sodium metaborate 20 to 60 An alkali metal sulfite 20 to 60 An alkali metal bromide 1 to 5 An amino pyridine 1 to 20 The reaction product of a 2,4-diaminoaniline with a compound selected from the class oonsisting of those of the following formulae: RQ-CHO and R5COCOOH Parts R4 being selected from the class consisting of hydrogen and lower alkyl and R5 being lower alkyl 2 to4 A phenol 0 to 10 Parts Sodium sulfate 50 to 150 Ascorbic acid 0 to 3 Water to make 1000 7. The composition as defined in claim 1 containing up to 3 parts of ascorbic acid.

ROBERT C. GUNTHER.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A STORAGE STABLE DEVELOPER SOLUTION FOR THE PRODUCTION OF AZINE DYESTUFF IMAGES CONTAINING A 2,4-DIAMINOANILINE AND SODIUM METABORATE AS THE ONLY ALKALI FOR THE DEVELOPER. 